Fluid heater control apparatus



Feb. 10, 1953 R. F. DOTSON 2,628,033

FLUID HEATER CONTROL APPARATUS Filed Dec. 6, 1949 2 SHEETS-SHEET 1 //v I/EN TOR P055544 ft Dorso/v,

A T TORNE V Feb. 10, 1953 R. F. DOTSON 2,628,033

FLUID HEATER CONTROL APPARATUS Filed Dec. 6, 1949 2 SHEETS-SHEET 2 lNl/EN TOR 5055544 F 00 750M ZvM/m A T TOP/VEV Patented Feb. 10, 1953 UNITED STATES PATENT OFFICE FLUID HEATER- CONTROL APPARATUS Russell F. Dotson, Atlanta, Ga.

Application. December 6, 1949, Serial No. 131,473

.14 Claims- 1 This invention relates to fluid heater control apparatus and is particularly well adapted for gas fired installations.

In their efforts to achieve an acceptable degree of safety in this art, prior inventors have almost invariably introduced such complications as to render their devices costly and difficult to maintain. It has now been found that sin plicity in this field is highly consistent with maximum safety, and definitely preferable from the standpoints of cost and dependability.

Since apparatus of the type here involved usually comprises a main burner and a pilot burner, it is important that no fuel be supplied to the main burner while an attendant is lighting the pilot burner. Inasmuch as operation of the main burner valve in devices of the type here under consideration is controlled by bleeding fuel from one side of a diaphragm more rapidly than it is replaced from the fuel source, it follows that control of the bleed fuel will determine the opening and closing of the main burner valve. Accordingly, an interlocking arrangement has been provided herein to prevent kindling of the pilot burner at any time that gas can be bled from behind the diaphragm; and furthermore to prevent reopening of the bleed passage until after the pilot burner fuel primer has been released.

Whenever the fluid being heated has reached a temperature exceeding a. predetermined safe value, means has been provided for interrupting the flow of both bleed and pilot fuel, requiring manual priming to reestablish the flow of fuel to either the main or pilot burner. A thermocouple exposed to the pilot burner flame supplies current to an electromagnet at a value sufficient to maintain a valve in its open position but insufficient to initiate opening of the valve; hence a manual primer is provided to initiate the opening of such valve, whereupon the pilot burner can be started and the resulting thermocouple current Will then hold the valve in its open position.

When the temperature of the fluid being heated drops below a preset value, a thermosensitive element responds to permit the flow of bleed gas, and similarly, when the fluid temperature achieves a predetermined elevated value, the element closes a valve in the bleed gas line. A preferred form of actuator for this purpose assumes the form of a permanent magnet influencing a paramagnetic valve, the magnet being pivotally suspended from a thermally actuated lever having an adjustable fulcrum; and

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when the safe upper temperature limit has been exceeded, the permanent magnet assumes a position in which its flux opposes that of the ther mocouple supplied electromagnet. sufficiently for the valve to interrupt the flow of both pilot and bleed gas.

Among its many aspects, the present invention contemplates fluid heater control apparatus comprising a valve casing, a diaphragm dividing the casing into two chambers interconnected by an orifice; means defining a burner supply port, a pilot supply passage and a fuel inlet port communicating with one of the chambers, a valve connected With the diaphragm for registry with the burner supply port, means defining a bleed passage communicating with the other chamber, and a valve interposed in the bleed chamber. The pilot and bleed passages contain valves and suitable operators therefor, the preferred form contemplating an adjusting valve for pilot fuel, a stop valve for bleed fuel, a manual shutoff valve for bleed fuel, and a stop valve for both pilot and bleed fuel. The stop valve for bleed fuel is rendered responsive to the temperature of the fluid: being heated, and the stop valve for both pilot and bleed fuel is controlled by the joint effects of pilot burner temperature and temperature of'the fluid to be heated. Ihe combined pilot and bleed fuel shut-off valve located in a passage common to the pilot and bleed fuel is equipped with a manual operator for priming during a pilot kindling operation, which operator is rendered ineffective whenever the bleed fuel manual shut-off valve is open; and similarly, when the operator is in a priming position, the manual shut-:off valve cannot be opened.

The burner supply valve is biased towards its port closing position by means of a spring, inasmuch as the diaphragm by which it is car ried is arranged in a substantially vertical plane, sacrificing the biasing effect of gravity ordinari ly utilized in such structures for the added advantages of main burner low gas pressure cut-ofi and compactness. The burner valve preferably reciprocates between its extreme positions in a recess converging towards its port, the reduced portion of the recess havin a cross section substantially equal to that of the valve body.

The bleed passage contains a valve, preferably a paramagnetic ball, influenced by a paramagnetic operator magnetically coupled thereto,

fluid to be heated. The combined pilot and bleed fuel shut-off valve is maintained open against the biasing effect of gravity by an electroma netic means energized by thermal sensing means, the electromagnetic means being opposed in its effect by the magnetic means for controlling the paramagnetic bleed valve. The electromagnetic means preferably responds to pilot temperatures through the use of a thermocouple, and the opposing magnetic means preferably responds to fluid temperatures. The opposin magnetic means is preferably a permanent magnet movable about an adjustable axis to shift the bleed valve and a fluid temperature responsive element is preferably connected with the magnet to effect movement thereof.

Thus it will be recognized that a fluid temperature responsive valve, a manually operated valve, and a pilot temperature responsive valve are interposed in series in the passage travelled by bleed fuel.

Partially due to the lag in the opening and closing of the snap acting main burner supply valve, produced by differential pressure and throttling effects upon its flexible port engagin member, bleed fuel is supplied to the pilot burner just prior to the supply of fuel to the main burner.

The diaphragm and main burner valve biasing spring provides a low gas pressure cut-off for the main burner while permitting the pilot burner to continue operation. Furthermore, this biasing spring permits operation of the main burner only during periods when the gas supply pressure is sufficiently high to insure its efficient operation.

The objects of this invention include the achievement of the foregoing functions, in a practicable and simple manner by novel relationships of parts which can best be described Fig. 2 is a front elevation, on a somewhat larger scale, of the control apparatus of Fig. 1;

Fig. 3 is a sectional elevation, on a further enlarged scale, taken along line 33 of Fig. 2;

Fig. 4 is a fragmentary sectional elevation, on an enlarged scale, along line 44 of Fig. 2;

Fig. 5 is a fragmentary sectional plan view taken along line 55 of Fig. 3;

Fig. 6 is a fragmentary sectional elevation taken along line 66 of Fig. 5; and

Fig. 7 is a fragmentary sectional elevation taken along line 7-? of Fig. 2.

The invention has been depicted as applied to a gas water heater comprising a storage tank In having a head l2 and bottom 14, from which a depending skirt [6 extends to a pan l8 to define a firebox 20. A main burner 22 provided with the usual bottle mixer 24 is received on brackets 26 which are suitably secured to the pan 18. A mounting plate 28 secured to the forward portion of the firebox, supports the control apparatus of the present invention, generally depicted by reference character 39, whose orifice spud projects through an opening in the mounting plate into the bottle mixer, suitable clamping nuts 32 carried by the threaded spud, engaging opposite surfaces of the mounting plate. The control apparatus comprises a valve casing 34 having a cover plate 38, above which a lever housing 38 is supported, the upper end of which communicates with a fulcrum housing ii), which in turn receives a thermostatic element 6.2 intended to respond to temperatures of the fluid to be heated, in this case, water. An adjusting knob 44 is arranged at the front of the fulcrum housing 40, the functions of which will be described in the material to follow. Gas from a suitable source is conducted to the control apparatus through a suitable pipe line ie which communicates with an inlet nipple 48.

A pilot burner 5G is also located in the firebox 20, serving to ignite fuel supplied to the main burner 22. The pilot burner receives pilot fuel, as well as bleed fuel as will be described, through a tube 52 which communicates with the upper portion of the valve casing 34 as shown in Fig. 1. A thermocouple 5A is mounted above the pilot burner 59 so as to generate a current as result of pilot burner operation, the thermocouple being connected by its cable 56 with the terminals of an electromagnet 58 suitably supported on the valve casing 34.

As depicted in Fig. i, the storage tank is provided with the usual drop tube 6% and hot water outlet 62.

A diaphragm E l is clamped between the valve casing 38. and cover plate 36 by means of screws 6%, the diaphragm being penetrated by a small orifice 58 through which gas supplied by the nipple 48 to the internally threaded inlet port 1'8, can pass from a chamber ?2 formed at one side of the diaphragm to a chamber it formed at the other side thereof. In order to maintain the apparatus as compact as is consistent with highly satisfactory operation, the diaphragm Ed is composed of a relatively flexible material so that it can partake of sufficient movement to permit proper opening and closing of the main burner supply valve it. The valve comprises a rigid backing plate or disc 18 secured to an internally threaded collar Bii threaded to its proper position upon a stem 82, and a flexible seat engaging member 84 centrally clamped against the backing plate by means of a nut 85 likewise threaded on the stem 32. The valve stem 82 is provided with a head 88, between which and the flexible diaphragm $4, a relatively large rigid disc 98 is interposed. The diaphragm at is centrally clamped against the disc 93 by means of a nut 82 threaded on the stem 82. A reduced portion of the stem 32 projects beyond the main burner valve to serve as a guide pin 94 which is received in a tubular bearing 9?; formed centrally of the externally threaded nipple 98 which receives the orifice spud. A spring liiii is interposed between the valve casing cover 36 and the diaphragm 6 tending to urge the main burner valve it towards its seat H32 located at the lower end of a recess We formed in the valve casing, having a side wall it?) converging towards the burner supply port. The valve casing cover 3 1 is centrally threaded to receive a limiting stop Hi8 whose position can be adjusted by means of a screwdriver after removing the dust cover i If! in order to limit the maximum departure of the main burner supply valve l6 from its seat to conform with the requirements of burners of diflerentcapacities. It will be advantageous to describe the operation of the main burner supply valve at this point. Assuming that the valve if; has moved to its extreme right hand position as viewed in Fig. 3 to close its port, and assuming that the chambers '12 and i are filled with gas, and further assuming that there is a call for gas to the main burner, which will result in a bleeding of gas from the chamber 14 more rapidly than it can be replenished through the relatively small orifice 68 formed in the diaphragm, the forces tending to open the valve will consist of gas at the pressure supplied to chamber i2 acting on an area of the flexible seat engaging member 84 extending beyond the seat itself and gas at this same pressure acting on the portion of the diaphragm supported by the rigid disc 95; the opposing forces tending to maintain the valve closed consist of the pressure of the gas in chamber l2 acting on the exposed area of the backing plate i6 and gas at the pressur extant in chamber 14 acting on the rigid disc 90 and in addition, the force of the spring me. As soon as the summation of opening forces exceeds the opposing forces, the diaphragm and the valve stem 82 begin to move to the left as viewed in Fig. 3, but since gas at the pressure existing in chamber #2 will gain access to the space between the rigid backing plate 12 and flexible seat engaging member 8 3 of the valve, it will follow that the flexible seat engaging member as will tend to remain on its seat as long as its flexibility will permit. However, as soon as the diaphragm 54 has moved sufliciently far to the left, the flexible seat engaging member 84 will be snapped from its seat to produce a full fiow of gas to the burner almost immediately. When gas is no longer being bled from the chamber 14, its pressure will become equal to that prevailing in chamber 12, whereupon the diaphragm will tend to seek its neutral position insofar as the gas pressures alone are concerned, but the spring E09 biases the diaphragm and its valve towards the right as viewed in Fig. 3 so that the valve moves towards its seat with an ever diminishing distance from the convergent wall I95 to produce a throttling effect as the valve approaches its seat, which results in a cushioning effect which has been found to be so desirable during the closing operation.

Gas is bled from the chamber 14 through a passage H2 which communicates with a valve chamber H4 formed in the upper portion of the cover plate 35. The valve chamber He has a cylindrical wall H6 which is slightly downwardly inclined towards the right as viewed. in Fig. 3, the lowermost portion communicating with a passage H8 defining a seat for the paramagnetic valve ball housed in the chamber H4.

The upper end of the valve chamber I IQ is closed with respect to atmosphere by means of aplug I22. The passage H8 registers with a perforation i2t formed through the diaphragm, which in turn registers with a passage 12.5 formed in the,

valve casing 34. As clearly shown in Fig- 5 of the drawings, the passage I can be closed by means of a rotary valve I28 whose plug I30 has secured thereto a latching member I32 which serves as a handle to shift the valve through an angle of 90 from open to closed position. The passage I26 intersects a passage I34 at right angles thereto, one end of which terminates at its intersection with a ball chamber I36, and the other end of which is internally threaded to receive a pilot flow adjusting screw or valve 538 and a dust cover I40. The valve 138 is provided with a graduated. orifice forming portion Hi2 which provides a substantially circular, and therefore self-cleaning orifice in all of its positions to which it can be adjusted. This valve controls the flow of gas from the chamber 12 through a passage I44 which intersects the passage I34 at right angles.

It will be evident that the pilot gas passage (44 and the bleed gas passage I25 communicate with one another through the common passage I34, so that they will be jointly controlled by a valve ball I45 received in the ball chamber I36. The electromagnet 58, shown particularly in Figs. 6 and '7, as previously described, is energized by current from the thermocouple 54 in response to temperature conditions at the pilot burner. The core I48 of the electromagnet is threaded near its lower end to secure it at the upper end I of the ball chamber I36. The lowermost end of the core I48 is sharply tapered to obtain a concentration of flux, but the force of the magnet is never sufiicient in itself to elevate the ball I46 from the position shown in Fig. 6 in which it closes its passage I50, but the force of the electromagnet is sumcient when the pilot burner is operating to retain the ball hid in an elevated position once it has been raised into contact therewith- Accordingly, manually actuated means in the form of an operator or primer has been provided, comprising a rod I52 of non-magnetic material, having a tapered end I54 for engagement of the ball slightly below its center, so that when the rod is advanced towards the right as viewed in Fig. 5, the ball will be elevated into contact with the tapered end of the core M8. The rod I52 is received within a bore I56 which communicates with the lower portion of the ball chamber I35. The rod is preferably biased outwardly by means or a spring I58 which bears upon a shoulder I69 formed in the bore and upon a collar IE2 carried by the rod. The rod is centered in the bore I55 by means of a bushing i54 threaded into the end of the bore. The outer end of the rod 52 carries a. push, button I56 by which the rod can be depressed in opposition'to the spring I58 to elevate the ball I45, but. only during such times as the bleed valve I28 closes its passage I25. This is accomplished by arranging the valve handle or latching member I32 so that it will always assume a position in the path of the pus-h button I63 whenever the bleed valve I28 assumes an open position. Moreoven-once the latching member 32 has been swung counterclockwise sufficiently to permit depression of the push button I56, the latching member l32 cannot be moved clockwise to open its valve: I28 so long as the push button I35 remains depressed. Thus, there is no possibility of the main burner being supplied with gas during a priming operation. It is also impossible to adjust the pilot flow valve i318 while the bleed gas valve I28 is open, since the latching member or operator I32 likewise obstructs access to the valve I38 and its dust cover I48 when the bleed gas valve I28 is open, but counterclockwise movement of the latching member or operator I32 sufliciently to afford access to the valve I38 will assure closure of the valve I28. The latching memberor operator I32 is provided with a suitable limiting stop I 68 to prevent such excessive movement of the valve I 28 as would defeat the purpose of this arrangement. With the valve ball M6 in its elevated position, both pilot and bleed gas can flow downwardly through the passage I58 to its intersection with a passage no terminating in a threaded nipple I12 to which the pilot tube 52 is secured in fluid' tight relation.

The lever housing 38 surmounting the valve casing, receives in its upper end a depending; tu-

bular portion I'M of the fulcrum housing 40.

The housing 40 is provided with an internally threaded opening H6 which receives an internally and externally threaded bushing I2 8 Whose inner end is bifurcated to define a guide slot I88 to limit lateral movement of a fulcrum plate I82. The plate I82 contains an opening I84 which loosely receives the reduced end I86 of a threaded shaft I88 received by the internal threads of the bushing I18. The adjusting knob 84 is secured to the exposed end of the shaft I88 to shift the axis about which the plate I82 will move during its operation. The lower portion of the plate I82 is biased towards the right as viewed in Fig. 3, by means of a spring I99 which is centered and retained by means of a screw I92 which also serves to maintain the lever housing and fulcrum housing in assembled relationship. The lower end of the plate I82 is drilled to receive the upper end of a resilient lever Its, the upper portion of which contains a loop I55 which will yield under severe conditions to prevent damage to the operating parts, and at the same time permitting them to retain their preset relationships. The lower end of the lever I6 2 receives a link I68 pivotally connecting it with a permanent magnet 2% whose lower end traverses a path lying below, though spaced from, the center of the ball hi6. As will be evident from an inspection of Fig. 3, the permanent magnet receives the link I98 near one corner thereof, so that in its terminal right hand position as shown in Fig. 3, the magnet assumes a position which is somewhat inclined to the vertical in the interests of compactness. This permanent magnet 266 also controls the valve ball I26 located in the valve chamber H4, serving to control the flow of bleed gas from the chamber I4 in response to temperature conditions of the fluid to be heated. When the system requires operation of the main burner as determined by the temperature of the fluid to be heated, the e lever I94 moves towards the left as viewed in Fig. 3, carrying the permanent magnet 266 with it until such time as the lowermost end of the permanent magnet approaches the ball I26 sufhcien ly closely to cause relative movement of the magnet and ball. At this point, the magnet will swing about the pivot defined by the link I98 to the most proximate position with respect to the ball permitted by the position of the lever I94. Under these conditions, the ball I26 will be lifted towards the upper portion of its inclined chamber to open the passage I I8 to the flow of bleed gas passing from the chamber I4 through the passage I I2. As the fluid to be heated achieves the temperature corresponding to the predetermined setting effected by adjustment of the knob 44, the lever I94 begins moving towards the right as viewed in Fig. 3, effecting a corresponding direction of movement of the permanent magnet 266, the permanent magnet remaining at all times in as close proximity to the ball I26 as the position of the lever I54 will permit, until finally the force imposed by the lever I94 upon the permanent magnet 206 exceeds the attractive force between the permanent magnet and the ball I25, at which time the magnet will be pulled away from the ball and the passage H8 will be closed to block the further flow of the gas from the chamber I4.

The fulcrum housing 46 supports a lever 292 upon a pivot 204, the lower end of the lever terminating in a point 266 which bears upon a portion of the fulcrum plate I 82 intermediate the shaft I88 and the spring I90. The upper end of the lever 282 is engaged by a rod 268 which transmits movements of its housing 2H] in response to expansion and contraction of the housing resulting from temperature conditions to which it is subjected. In this case, the housing member 2H! may assume the form of a copper tube having a closed end, the tube being depicted in Fig. 1 as in contact with the wall of a storage tank of a water heater. It will be clear than an increase in temperature of the fluid to be heated will result in an expansion of the tube, reducing the force of the rod 268 upon the lever 262, resulting in movement of the lever I94 towards the right under the influence of its biasing spring I90. Conversely, when the liquid to be heated has cooled to a predetermined point, the eifects will be reversed, the lever I94 will move towards the left and the valve I 26 will be lifted from its seat.

Should the temperature of the fluid to be heated rise above that for which the knob 44 has been adjusted, the lever I94 will continue to move towards the right, carrying the permanent magnet 266 with it, until such time as the flux of the permanent magnet 266 will 0ppose that of the electromagnet sufliciently to cause the valve ball I46 to drop to its seat to close the passage I 56, thereby obstructing the flow of both pilot gas and bleed gas, calling for a manual reset before service can be resumed. As previously described, such a reset would require closing the bleed gas valve I28 in order to depress the push button I66 to elevate the ball I46 and permit the passage of pilot gas so that the pilot can be ignited. Then, before the main burner can go into operation, the push button I66 must be released and the operator I32 restored to its obstructing position to open the bleed gas valve I28. It should be noted in this behalf that as long as the permanent magnet assumes a position in which its fluX opposes that of the electromagnet sufficiently to prevent retention of the ball in an elevated position, operation of the system cannot be resumed since the ball I46 will always return to its seat as soon as the push button I66 has been released.

One condition under which such complete shut-down of the main and pilot burners is produced, occurs when there is stoppage due to dirt or other causes of the diaphragm orifice 68. Under these conditions, no gas can pass directly from the chamber I2 into the chamber I4 through the orifice, and accordingly, excessive heating will eventually cause the ball I46 to drop to its seat and block the passage of both pilot and bleed gas. As soon as the ball I46 drops to its seat, continued flow of pilot gas through passages I44 and I34 will produce a flow through passage I26, back through the passage H8 and past the valve I26, through the passage II2 into chamber I4 until gas pressure in the chamber "I4 builds up sufiiciently to move the main burner valve I6 to its seat I02, preventing the further new of fuel to the main burner until uch time as the system may be manually reset.

This control apparatus readily adapts itself to permit a shutting down of the main burner for a protracted period while maintaining operation of the pilot burner. This is accomplished simply by moving the latching member or operator I32 counterclockwise to a position closing the bleed gas valve I28 and maintaining the operator I 32 in this position for such period of time as may be desired. To restore the system to operation under these conditions, it is merely necessary to rotate the operator I32 clockwise until the bleed gas valve I28 is reopened.

The knob 44 can be adjusted to move the axis or fulcrum about which the lever I94 is pivoted to adjust the temperature to which the fluid to be heated will be raised. In the event that it is desired to produce a complete shut-down of the system by adjustments of the knob 44, it is merely necessary to turn it to a position in which the permanent magnet 208 will oppose the electromagnet 58 sufficiently to cause the ball I45 to drop to its seat just as in the case of excessive heating of the fluid. Here again, when it is desired to restore the system to operation, manual resetting will be required. This will be possible of course, only after the knob has been shifted from the aforesaid position to a setting of temperature within the operating limits-of the system.

It will be understood that in order for the electromagnet and permanent magnet to influence themselves to those skilled in the art after reading this specification, just as such variations have already occurred to the present inventor. Accordingly, the invention should not be restricted to the specific structure depicted and described beyond the scope of the appended claims.

I claim:

1. Fluid heater control apparatus comprising a valve casing, a diaphragm dividing said casing int-o two chambers interconnected by an orifice; means defining a burner supply port, a pilot supply passage and a fuel inlet port communicating with one of said chambers; a valve connected with said diaphragm for registry with said burner supply port, means defining a bleed passage communicating with the other of said chambers, a valve interposed in said bleed passage, a valve interposed in said pilot supply passage, a manual operator for said pilot supply valve and means interconnected with said bleed passage valve obstructing said operator when said bleed passage valve is open.

2. Fluid heater control apparatus comprising a valve casing, a diaphragm dividing said casing into two chambers interconnected by an orifice; means defining a burner supply port, a pilot supply passage and a fuel inletport communicating with one of said chambers; a valve connected with said diaphragm for registry with said burner supply port, means defining a bleed passage communicating with the other of said chambers, a valve interposed in said bleed passage, a, valve interposed in said pilot supply passage, a manual operator for said pilot valve, a manual operator for said bleed valve providing means interconnected therewith obstructing said pilot valve operator while said bleed valve is open.

3. Fluid heater control apparatus comprising a valve casing, a diaphragm dividing said easing into two chambers interconnected by an orifice; means defining a burner supply port, a pilot supply passage and a fuel inlet port communicating with one of said chambers; a valve connected with said diaphragm for registry with said burner supply port, means defining a bleed passage communicating with the other of said chambers, a

valve interposed in said bleed passage, a, valve interposed in said pilot supply passage, manual operator for said bleed and pilot valves, and means interconnected with said pilot valve operator obstructing said bleed valve operator when said pilot valve operator occupies a valve opening position.

4. Fluid heater control apparatus comprising a valve casing, a diaphragm dividing said easing into two chambers interconnected by an orifice; means defining a burner supply port, a pilot supply passage'and a fuel inlet .port communicating with one of said chambers; a valve connected with said diaphragm for registry with said burner supply port, means defining a bleed passage communicating with the other of said chambers, a valve interposed in said bleed passage, a valve interposed in said pilot supply passage, said passages communicating beyond said valves with a common passage, and a valve interposed in said common passage.

5. Fluid heater control apparatus comprising a valve casing, a diaphragm dividing said easing into two chambers interconnected by an orifice;

means defining a burner supply port, a pilot supply passage and a fuel inlet port communicating with one of said chambers; a valve connected with said diaphragm for registry with said burner supply port, means defining a bleed passage communicating with the other of .said chambers, a valve interposed in said bleed passage, means defining a passage common to said bleed and pilot passages, a valve interposed in said common passage, an operator for said common passage valve, and means obstructing said operator when said bleed passage valve is open.

6. Fluid heater control apparatus comprising a valve casing, a diaphragm dividing said easing into two chambers interconnected by an orifice; means defining a burner supply port, a pilot supply passage and a fuel inlet port communicating with one of said chambers; a, valve connected with said diaphragm for registry with said burner supply port, means defining a bleed passage communicating with the other of said chambers, a paramagnetic valve interposed in said bleed passage, a paramagnetic operator magnetically coupled with said bleed passage valve, and thermalsensing'means connected with said operator.

7.. Fluid heater control apparatus comprising a valve casing, a diaphragm dividing said casing into two chambers interconnected by an orifice; means defining a, burner supply port, a pilot supply passage and a fuel inlet port communicating with one of said chambers; a valve connected with said diaphragm for registry with saidburner supply port, means defining a bleed passage communicating with the other of said chambers, a valve interposed in said bleed passage, means defining a passage common to said bleed and pilot passages, a valve interposed in said common passage, electromagnetic means for holding said common passage valve open, thermal sensing means connected with said electromagnetic means for energizing the same, and thermally actuated magnetic means controlling said bleed valve and of opposite polarity to the field of said electromagnetic means.

8. Fluid heater control apparatus comprising a valve casing, a diaphragm dividing said casing into two chambers interconnected by an orifice; means defining a burner supply port, a pilot supply passage and a fuel inlet port communicating with one of said chambers; a valve connected with said diaphragm for registry with said burner supply port, means defining a bleed passage communicating with the other of said chambers, a valve interposed in said bleed passage, a valve interposed in said pilot passage, electromagnetic means responsive to pilot temperature for holding said pilot valve open, and magnetic means responsive to fluid temperature to oppose the field of said electromagnetic means.

9. Fluid heater control apparatus comprising a valve casing, a diaphragm dividing said casing into two chambers interconnected by an orifice; means defining a burner supply port, a pilot supply passage and a fuel inlet port communicating with one of said chambers; a valve connected with said diaphragm for registry with said burner supply port, means defining a bleed passage communicating with the other of said chambers, a valve interposed in said bleed passage, a valve interposed in said pilot passage, an operator for said bleed valve, said operator obstructing access to said pilot valve when said bleed valve is open.

10. Fluid heater control apparatus comprising a valve casing, a diaphragm dividing said casing into two chambers interconnected by an orifice; means defining a burner supply port, a pilot supply passage and a fuel inlet port communicating with one of said chambers; a valve connected with said diaphragm for registry with said burner supply port, means defining a bleed passage communicating with the other of said chambers, a valve interposed in said bleed passage, said passages combining to form a common passage, a valve in said common passage biased towards a closed position, an electromagnet supporting said biased valve. in open position, a pilot responsive thermocouple energizing said electromagnet, and a manual operator for shifting said biased valve towards said electromagnet.

l1. Fluid heater control apparatus comprising a valve casing, a diaphragm dividing said casing into two chambers interconnected by an orifice; means defining a burner supply port, a pilot supply passage and a fuel inlet port communicating with one of said chambers; a valve connected with said diaphragm for registry with said burner supply port, means defining ableed passage cornmunicating with the other of said chambers, a paramagnetic valve interposed in said bleed passage, a permanent magnet movable about an axis to shift said bleed valve, a fluid temperature responsive element connected with said magnet to efiect movement thereof, and adjusting means for shifting said axis.

12. Fluid heater control apparatus comprising a valve casing, a diaphragm dividing said casing into two chambers interconnected by an orifice; means defining a burner supply port, a pilot supply passage and a fuel inlet port communicating with one of said chambers; a valve connected with said diaphragm for registry with said burner supply port, means defining a bleed passage communicating with the other of said chambers, a paramagnetic valve body interposed in said bleed passage, a movable magnet spaced from said bleed valve having a field directly operable on said bleed valve for shifting the same between passage opening and closing positions, and fluid temperature responsive means connected with said magnet for imparting valve shifting movement thereto.

l3. Fluid heater control apparatus comprising a valve casing, a diaphragm dividing said easing into two chambers interconnected by an orifice; means defining a burner supply port, a pilot supply passage and a fuel inlet port communicating with one of said chambers; a valve connected with said diaphragm for registry with said burner supply port, means defining a bleed passage communicating with the other of said chambers, a paramagnetic valve body interposed in said bleed passage, a pilot tube in fluid communication with said pilot and bleed passages, and means including a permanent magnet actuating said bleed valve responsive to fiuid temperature to supply bleed fuel to said pilot prior to opening of said burner supply valve.

14. Fluid heater control apparatus comprising a valve casing, a diaphragm dividing said easing into two chambers interconnected by an orifice; means defining a burner supply port, a pilot supply passage and a fuel inlet port communicating with one of said chambers; a valve connected with said diaphragm for registry with said burner supply port, means defining a bleed passage communicating with the other of said chambers, a gravity biased ball valve interposed in said bleed passage and tending to close the same, pilot temperature responsive means exerting a force sufficient to maintain said ball in open position but insufiicient to elevate said ball to open position, and an operator engageable with said ball to elevate it to open position.

RUSSELL F. DOTSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 22,068 Joesting Apr. 14, 1942 1,678,658 Thomas July 31, 1928 1,824,057 Robertshaw Sept. 22, 1931 2,159,617 Kronmiller May 23, 1939 2,261,092 Peterson Oct. 28, 1941 2,262,823 Stearns Nov. 18, 1941 2,262,825 Welliver NOV. 18, 1941 2,362,631 Harris Nov. 14, 1944 2,390,993 De Giers Dec. 18, 1945 

1. FLUID HEATER CONTROL APPARATUS COMPRISING A VALVE CASING, A DAIPHRAGM DIVIDING SAID CASING INTO TWO CHAMBERS INTERCONNECTED BY AN ORIFICE; MEANS DEFINING A BURNER SUPPLY PORT, A PILOT SUPPLY PASSAGE AND A FUEL INLET PORT COMMUNICATING WITH ONE OF SAID CHAMBERS; A VALVE CONNECTED WITH SAID DIAPHRAGM FOR REGISTRY WITH SAID BURNER SUPPLY PORT, MEANS DEFINING A BLED PASSAGE COMMUNICATING WITH THE OTHER OF SAID CHAMBERS, A VALVE INTERPOSED IN SAID BLEED PASSAGE, A VALVE INTERPOSED IN SAID PILOT SUPPLY PASSAGE, A MANUAL OPERATOR FOR SAID PILOT SUPPLY VALVE AND MEANS 